In order to determine the effect of GM-CSF plus G-CSF in combination in breast cancer patients receiving an effective induction regimen, we compared hematological recovery and peripheral blood progenitor cell (PBPC) mobilization according to colony-stimulating factor (CSF) support. Forty-three breast cancer patients were treated by TNCF (THP-doxorubicin, vinorelbine, cyclophosphamide, fluorouracil, D1 to D4) with CSF support: 11 patients received GM-CSF (D5 to D14); 16 patients G-CSF (D5 to D14) and 16 patients GM-CSF (D5-D14) plus G-CSF (D10-D14). Between two subsequent cycles, progenitor cells were assessed daily, from D13 to D17. The WBC count was similar for patients receiving G-CSF alone or GM-CSF plus G-CSF, but significantly greater than that of patients receiving GM-CSF alone (P<0.001). The GM-CSF plus G-CSF combination led to better PBPC mobilization, with significantly different kinetics (P<0.001) and optimal mean values of CFU-GM, CD34+ cells and cells in cycle, at D15 compared to those obtained with G-CSF or GM-CSF alone. The significantly greater PBPC mobilization obtained with a CSF combination by D15 could be of value for PBPC collection and therapeutic reinjection after high-dose chemotherapies.